The present invention relates to compounds for delivering active agents, and particularly biologically or chemically active agents such as, for example, bioactive peptides and the like. These compounds are used as carriers to facilitate the delivery of a cargo to a target. The carriers are modified amino acids and are well suited to form non-covalent mixtures with biologically-active agents for oral administration to animals. Methods for the preparation and for the administration of such compositions are also disclosed.
Conventional means for delivering active agents are often severely limited by biological, chemical, and physical barriers. Typically, these barriers are imposed by the environment through which delivery occurs, the environment of the target for delivery, or the target itself.
Biologically or chemically active agents are particularly vulnerable to such barriers. For example in the delivery to animals of pharmacological and therapeutic agents, barriers are imposed by the body. Examples of physical barriers are the skin and various organ membranes that must be traversed before reaching, a target. Chemical barriers include, but are not limited to, pH variations, lipid bi-layers, and degrading enzymes.
These barriers are of particular significance in the design of oral delivery systems. Oral delivery of many biologically or chemically active agents would be the route of choice for administration to animals if not for biological, chemical, and physical barriers such as varying pH in the gastro-intestinal (GI) tract, powerful digestive enzymes, and active agent impermeable gastro-intestinal membranes. Among the numerous agents which are not typically amenable to oral administration are biologically or chemically active peptides, such as calcitonin and insulin; polysaccharides, and in particular mucopolysaccharides including, but not limited to, heparin; heparinoids; antibiotics;.and other organic substances. These agents are rapidly rendered ineffective or are destroyed in the gastro-intestinal tract by acid hydrolysis, enzymes, or the like.
Earlier methods for orally administering vulnerable pharmacological agents have relied on the co-administration of adjuvants (e.g., resorcinols and non-ionic surfactants such as polyoxyethylene oleyl ether and n-hexadecylpolyethylene ether) to increase artificially the permeability of the intestinal walls, as well as the co-administration of enzymatic inhibitors (e.g., pancreatic trypsin inhibitors, diisopropylfluorophosphate (DFF) and trasylol) to inhibit enzymatic degradation.
Liposomes have also been described as drug delivery systems for insulin and heparin. See, for example, U.S. Pat. No. 4,239,754; Patel et al. (1976), FEBS Letters, Vol. 62, pg. 60; and Hashimoto et al. (1979), Endocrinology Japan, Vol. 26, pg. 337.
However, broad spectrum use of such drug delivery systems is precluded because: (1) the systems require toxic amounts of adjuvants or inhibitors; (2) suitable low molecular weight cargos, i.e. active agents, are not available; (3) the systems exhibit poor stability and inadequate shelf life; (4) the systems are difficult to manufacture; (5) the systems fail to protect the active agent (cargo); (6) the systems adversely alter the active agent; or (7) the systems fail to allow or promote absorption of the active agent.
More recently, microspheres of artificial polymers of mixed amino acids (proteinoids) have been used to deliver pharmaceuticals. For example, U.S. Pat. No. 4,925,673 describes drug-containing proteinoid microsphere carriers as well as methods for their preparation and use. These proteinoid microspheres are useful for the delivery of a number of active agents.
There is still a need in the art for simple, inexpensive delivery systems which are easily prepared and which can deliver a broad range of active agents.
Compositions which are useful in the delivery of active agents arc provided. These compositions are include at least one active agent, and preferably a biologically or chemically active agent, and at least one of the following compounds I-CXXIII, or salts thereof.
It has been discovered that organic acid compounds, and their salts, having an aromatic amide group, having a hydroxy group substituted in the ortho position on the aromatic ring, and a lipophilic chain with from about 4 carbon atoms to about 20 atoms in the chain are useful as carriers for the delivery of active agents. In a preferred form the lipophilic chain can have from 5 to 20 carbon atoms.
Compositions comprising the carrier compounds discussed above and active agents have been shown effective in delivering active agents to selected biological systems. These compositions include at least one active agent which is preferably a biologically or chemically active agent, and at least one carrier compound having the formula
2-HOxe2x80x94Arxe2x80x94CONR8xe2x80x94R7xe2x80x94COOH
wherein Ar is a substituted or unsubstituted phenyl or naphthyl;
R7 is selected from the group consisting of C4 to C20 alkyl, C4 to C20 alkenyl, phenyl, naphthyl, (C1 to C10 alkyl) phenyl, (C1 to C10 alkenyl) phenyl, (C1 to C10 alkyl) naphthyl, (C1 to C10 alkenyl) naphthyl, phenyl (C1 to C10 alkyl), phenyl (C1 to C10 alkenyl), naphthyl (C1 to C10 alkyl), and naphthyl (C1 to C10 alkenyl);
R8 is selected from the group consisting of. hydrogen, C1 to C4 alkyl, C1 to C4 alkenyl, hydroxy, and C1 to C4 alkoxy;
R7 is optionally substituted with C1 to C4 alkyl, C1 to C4 alkenyl, C1 to C4 alkoxy, xe2x80x94OH, xe2x80x94SH and xe2x80x94CO2R9 or any combination thereof;
R9 is hydrogen, C1 to C4 alkyl or C1 to C4 alkenyl;
R7 is optionally interrupted by oxygen, nitrogen, sulfur or any combination thereof;
With the proviso that the compounds are not substituted with an amino group in the position alpha to the acid group, or salts thereof.
The preferred R6 groups are of C4 to C20 alkyl and C4 to C20 alkenyl. The most preferred R6 groups are C5 to C20 alkyl and C5 to C20 alkenyl.
A preferred carrier compound can have the formula 
wherein R7is defined above.
Further contemplated by the present invention are dosage unit forms that include these compositions.
Also contemplated is a method for preparing these compositions which comprises mixing at least one active agent with. at least one compound as described above, and optionally, a dosing vehicle.
In an alternative embodiment, these non-toxic compounds are orally administered to animals as part of a delivery system by blending or mixing the compounds with an active agent prior to administration.
Further provided is a method for the preparation of a compound having the formula 
Wherein 
R1 is C3-C24 alkyl, C2-C20 alkenyl, C2-C20 alkyne, cycloalkyl, or aromatic;
R2 is hydrogen, C1-C4 alkyl, or C2-C4 alkenyl; and
R3 is C1-C7 alkyl, C3-C10 cycloalkyl, aryl, thienyl, pyrrolo, or pyridyl, where R3 is optionally substituted by one or more C1-C5 alkyl group, C2-C4 alkenyl group, F, Cl, OH, SO2, COOH, or SO3H;
said method comprising
a) reacting in water and the presence of a base, a compound having the formula 
xe2x80x83with a compound having the formula
R3xe2x80x94Yxe2x80x94X,
wherein Y, R1, R2, and R3 are as above and X is a leaving group.